Inflatable structures have advantages such as greater portability and significantly smaller storage volumes over solid structures. Inflatable structures are used for temporary emergency shelters, fast deploying military structures, and masonry construction framing. In the field of dome theaters there are two families of air driven structures, purely inflatable structures and inflatable/solid structure hybrids.
In purely inflatable structures, structural integrity is provided through positive air pressure. For example, a single spherically tailored fabric shell is inflated using positive air pressure, like an inflated balloon. This structure is used in current portable dome theater implementations (i.e. Starlab from Learning Technologies, GoDome™ from e-Planetarium™). While providing a smooth concave screen surface, the main disadvantage of this design is the need for an airlock to prevent the positive air pressure from escaping while people enter or leave the shell.
There are many purely inflatable structures that do not require an airlock. For example, inflatable tent structures have inflatable support tubes with a fabric shell draped over the tubes. Another example has two concentric fabric shells that are joined through a series of ribs which hold the shells at a fixed separation when positive air pressure is applied. Other structures are shown in U.S. Pat. Nos. 3,742,658, 4,288,947, and 4,807,405. While all of these purely inflatable structures offer open doorway capability, none of them achieves a smooth concave screen surface.
In inflatable/solid structure hybrids, negative air pressure between a screen and an outer shell is used to draw a concave screen taut and smooth. The outer shell may be a solid structure such as in U.S. Pat. No. 3,998,522, or a fabric membrane stretched over a solid framing network such as in U.S. Pat. No. 4,022,522. This design form is not purely inflatable and is therefore less portable and less compact in storage.
There is a need for improved inflatable structures and methods.